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Re: [Libguestfs] [PATCH 03/12] mountable: Implement Mountable support for all apis which take it



On Thu, Feb 07, 2013 at 03:57:49PM +0000, Matthew Booth wrote:
> A Mountable is passed from the library to the daemon as a string. The daemon
> stub parses it into a mountable_t, which it passes to the implementation.
> 
> Update all implementations which now take a mountable_t.
> ---
>  daemon/blkid.c      | 33 +++++++++++++++++++++++-----
>  daemon/daemon.h     | 41 ++++++++++++++++++++++++++++++++++
>  daemon/ext2.c       | 15 ++++++++++---
>  daemon/guestfsd.c   | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++---
>  daemon/labels.c     | 16 ++++++++++++--
>  daemon/mount.c      | 49 +++++++++++++++++++++++++++++++++--------
>  generator/c.ml      | 12 +++++++++-
>  generator/daemon.ml | 11 +++++++---
>  8 files changed, 213 insertions(+), 27 deletions(-)
> 
> diff --git a/daemon/blkid.c b/daemon/blkid.c
> index 64919dd..d54ac22 100644
> --- a/daemon/blkid.c
> +++ b/daemon/blkid.c
> @@ -67,21 +67,42 @@ get_blkid_tag (const char *device, const char *tag)
>  }
>  
>  char *
> -do_vfs_type (const char *device)
> +do_vfs_type (const mountable_t *mountable)
>  {
[...]
> +    default:
> +      reply_with_error ("Invalid mountable type: %i", mountable->type);
> +      return NULL;
> +  }
>  }

Lots of this code has these error cases.  However it would be much
simpler if the error case was handled by the generator, and my reading
of RESOLVE_MOUNTABLE is that it already *is* handled by the generator.
So you could assume that mountable->type would never be anything else
and replace the 'default' case with a call to abort () (even better if
GCC gave us a way to say the default case never happens, but that
doesn't seem to be possible).

There's even a possibility that these error cases are wrong because
they call reply_with_error twice along the error path (which results
in protocol desynchronization).

> +    if (strncmp ((string), "btrfsvol:", strlen ("btrfsvol:")) == 0) {   \

Better to use STRPREFIX here.

> +      RESOLVE_DEVICE((string), cancel_stmt, fail_stmt);                 \

Do we need parens around the *_stmts?  (I'm not sure ...)

> @@ -257,7 +262,7 @@ and generate_daemon_actions () =
>              (function FileIn _ | FileOut _ -> false | _ -> true) args in
>          let style = ret, args' @ args_of_optargs optargs, [] in
>          pr "  r = do_%s " name;
> -        generate_c_call_args style;
> +        generate_c_call_args ~in_daemon:true style;

Is this a bug in existing code?  It may need to be separately
backported if so.

The rest looks fine.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v


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